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Search Results: 1 - 10 of 26929 matches for " Martin Schulze "
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Der "imperial turn" in der Geschichte des Russl ndische Reiches.
Schulze Wessel, Martin,Staliunas, Darius,Dolbilov, Michail
Zeitenblicke , 2007,
Parameter-dependent Edge Operators
C. -I. Martin,B. -W. Schulze
Mathematics , 2009,
Abstract: We study parameter-dependent operators on a manifold with edge and construct new classes of elliptic elements in the corner calculus on an infinite cone with a singular base
Improved automatic computation of Hessian matrix spectral bounds
Moritz Schulze Darup,Martin M?nnigmann
Mathematics , 2015,
Abstract: This paper presents a fast and powerful method for the computation of eigenvalue bounds for Hessian matrices $\nabla^2 \varphi(x) $ of nonlinear functions $\varphi: U \subseteq R^n\rightarrow R$ on hyperrectangles $B \subset U$. The method is based on a recently proposed procedure for an efficient computation of spectral bounds using extended codelists. Both the previous approach and the one presented here substantially differ from established methods in that they do deliberately not use any interval matrices and thus result in a favorable numerical complexity of order $O(n)\,N(\varphi)$, where $N(\varphi)$ denotes the number of operations needed to evaluate $\varphi$ at a point in its domain. We improve the previous method by exploiting sparsity, which naturally arises in the underlying codelists.
Efficient Computation of Spectral Bounds for Hessian Matrices on Hyperrectangles for Global Optimization
Moritz Schulze Darup,Martin Kastsian,Stefan Mross,Martin M?nnigmann
Mathematics , 2012, DOI: 10.1007/s10898-013-0099-1
Abstract: We compare two established and a new method for the calculation of spectral bounds for Hessian matrices on hyperrectangles by applying them to a large collection of 1522 objective and constraint functions extracted from benchmark global optimization problems. Both the tightness of the spectral bounds and the computational effort are assessed. Specifically, we compare eigenvalue bounds obtained with the interval variant of Gershgorin's circle criterion [2,6], Hertz and Rohn's [7,16] method for tight bounds of interval matrices, and a recently proposed Hessian matrix eigenvalue arithmetic [12], which deliberately avoids the computation of interval Hessians.
Diagnostic Approach for the Differentiation of the Pandemic Influenza A(H1N1)v Virus from Recent Human Influenza Viruses by Real-Time PCR
Martin Schulze,Andreas Nitsche,Brunhilde Schweiger,Barbara Biere
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009966
Abstract: The current spread of pandemic influenza A(H1N1)v virus necessitates an intensified surveillance of influenza virus infections worldwide. So far, in many laboratories routine diagnostics were limited to generic influenza virus detection only. To provide interested laboratories with real-time PCR assays for type and subtype identification, we present a bundle of PCR assays with which any human influenza A and B virus can be easily identified, including assays for the detection of the pandemic A(H1N1)v virus.
Lattice Electrons on a Cylinder Surface in the Presence of Rational Magnetic Flux and Disorder
Christian Schulze,János Hajdu,Bodo Huckestein,Martin Janssen
Physics , 1997, DOI: 10.1007/s002570050398
Abstract: We consider a disordered two-dimensional system of independent lattice electrons in a perpendicular magnetic field with rigid confinement in one direction and generalized periodic boundary conditions (GPBC) in the other direction. The objects investigated numerically are the orbits in the plane spanned by the energy eigenvalues and the corresponding center of mass coordinate in the confined direction, parameterized by the phase characterizing the GPBC. The Kubo Hall conductivity is expressed in terms of the winding numbers of these orbits. For vanishing disorder the spectrum of the system consists of Harper bands with energy levels corresponding to the edge states within the band gaps. Disorder leads to broadening of the bands. For sufficiently large systems localized states occur in the band tails. We find that within the mobility gaps of bulk states the Diophantine equation determines the value of the Hall conductivity as known for systems with torus geometry (PBCs in both directions). Within the spectral bands of extended states the Hall conductivity fluctuates strongly. For sufficiently large systems the generic behavior of localization-delocalization transitions characteristic for the quantum Hall effect are recovered.
Functional Connectivity of Pain-Mediated Affect Regulation in Borderline Personality Disorder
Inga Niedtfeld, Peter Kirsch, Lars Schulze, Sabine C. Herpertz, Martin Bohus, Christian Schmahl
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0033293
Abstract: Affective instability and self-injurious behavior are important features of Borderline Personality Disorder. Whereas affective instability may be caused by a pattern of limbic hyperreactivity paired with dysfunctional prefrontal regulation mechanisms, painful stimulation was found to reduce affective arousal at the neural level, possibly underlying the soothing effect of pain in BPD. We used psychophysiological interactions to analyze functional connectivity of (para-) limbic brain structures (i.e. amygdala, insula, anterior cingulate cortex) in Borderline Personality Disorder in response to painful stimulation. Therefore, we re-analyzed a dataset from 20 patients with Borderline Personality Disorder and 23 healthy controls who took part in an fMRI-task inducing negative (versus neutral) affect and subsequently applying heat pain (versus warmth perception). Results suggest an enhanced negative coupling between limbic as well as paralimbic regions and prefrontal regions, specifically with the medial and dorsolateral prefrontal cortex, when patients experienced pain in addition to emotional arousing pictures. When neutral pictures were combined with painful heat sensation, we found positive connectivity in Borderline Personality Disorder between (para-)limbic brain areas and parts of the basal ganglia (lentiform nucleus, putamen), as well areas involved in self-referential processing (precuneus and posterior cingulate). We found further evidence for alterations in the emotion regulation process in Borderline Personality Disorder, in the way that pain improves the inhibition of limbic activity by prefrontal areas. This study provides new insights in pain processing in BPD, including enhanced coupling of limbic structures and basal ganglia.
Voxel-Based Morphometry in Women with Borderline Personality Disorder with and without Comorbid Posttraumatic Stress Disorder
Inga Niedtfeld I, Lars Schulze, Annegret Krause-Utz, Traute Demirakca, Martin Bohus, Christian Schmahl
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065824
Abstract: Patients with Borderline Personality Disorder (BPD) showed reduced volume of amygdala and hippocampus, but similar findings are evident in Posttraumatic Stress Disorder (PTSD). Applying voxel-based morphometry (VBM) in a larger cohort of patients with BPD, we sought to extend earlier findings of volume abnormalities in limbic regions and to evaluate the influence of co-occurring PTSD in BPD patients. We used voxel-based morphometry to study gray matter volume (GMV) in 60 healthy controls (HC) and 60 patients with BPD. Subgroup analyses on 53 patients concerning the role of co-occurring PTSD were conducted. Additionally, regression analyses were calculated to assess the relation between borderline symptom severity as well as dissociative experiences and GMV. Differences in local GMV between patients with BPD and HC were observed in the amygdale and hippocampus as well as in the fusiform and cingulate gyrus. Co-occurring PTSD was accompanied by increased GMV in the superior temporal gyrus and dorsolateral prefrontal cortex. Independent of co-occurring PTSD, severity of BPD symptoms predicted smaller GMV in the amygdala and dorsal ACC. Dissociation was positively related to GMV in the middle temporal gyrus. We could replicate earlier findings of diminished limbic GMV in patients with BPD and additionally show that patients with co-morbid PTSD feature increased GMV in prefrontal regions associated with cognitive control.
Effects of Cationic Antimicrobial Peptides on Liquid-Preserved Boar Spermatozoa
Martin Schulze, Christof Junkes, Peter Mueller, Stephanie Speck, Karin Ruediger, Margitta Dathe, Karin Mueller
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0100490
Abstract: Antibiotics are mandatory additives in semen extenders to control bacterial contamination. The worldwide increase in resistance to conventional antibiotics requires the search for alternatives not only for animal artificial insemination industries, but also for veterinary and human medicine. Cationic antimicrobial peptides are of interest as a novel class of antimicrobial additives for boar semen preservation. The present study investigated effects of two synthetic cyclic hexapeptides (c-WFW, c-WWW) and a synthetic helical magainin II amide derivative (MK5E) on boar sperm during semen storage at 16°C for 4 days. The standard extender, Beltsville Thawing Solution (BTS) containing 250 μg/mL gentamicin (standard), was compared to combinations of BTS with each of the peptides in a split-sample procedure. Examination revealed peptide- and concentration-dependent effects on sperm integrity and motility. Negative effects were more pronounced for MK5E than in hexapeptide-supplemented samples. The cyclic hexapeptides were partly able to stimulate a linear progressive sperm movement. When using low concentrations of cyclic hexapeptides (4 μM c-WFW, 2 μM c-WWW) sperm quality was comparable to the standard extender over the course of preservation. C-WFW-supplemented boar semen resulted in normal fertility rates after AI. In order to investigate the interaction of peptides with the membrane, electron spin resonance spectroscopic measurements were performed using spin-labeled lipids. C-WWW and c-WFW reversibly immobilized an analog of phosphatidylcholine (PC), whereas MK5E caused an irreversible increase of PC mobility. These results suggest testing the antimicrobial efficiency of non-toxic concentrations of selected cyclic hexapeptides as potential candidates to supplement/replace common antibiotics in semen preservation.
Experimentally induced incomplete burst fractures - a novel technique for calf and human specimens
René Hartensuer, Adam Gasch, Dominic Gehweiler, Steffen Schanz, Martin Schulze, Lars Matuszewski, Martin Langer, Michael J Raschke, Thomas Vordemvenne
BMC Musculoskeletal Disorders , 2012, DOI: 10.1186/1471-2474-13-45
Abstract: The presented method resulted in fracture morphology, found in clinical classification systems like the Magerl classification. In the calf spine samples, 70% displayed incomplete burst fractures corresponding to type A3.1 and A3.2 fractures. In all human samples, superior incomplete burst fractures (Magerl A3.1) were identified by an independent radiologist and spine surgeon.The presented set up enables the first experimental means to reliably model and study distinct incomplete burst fracture patterns in an in vitro setting. Thus, we envisage this protocol to facilitate further studies on spine fracture treatment of incomplete burst fractures.The treatment of incomplete burst fractures is one of the most controversially discussed issues in spinal traumatology.To our knowledge, neither clinical trials nor in vitro approaches have been able to reveal an exhaustive understanding of the pathology of this fracture type and its corresponding treatment needs to date.In the absence of clear evidence-based recommendations on how to treat this type of injury, a whole range of surgical and nonsurgical options can be found in literature [1].Holdsworth initially introduced the definition of "burst fractures" in 1970 [2], which was primarily considered to be a stable fracture. In contrast, clinical studies suggested [3,4], and experimental studies by Panjabi et al. [5] and Kifune et al. [6] revealed the instability of burst fractures. They observed that injuries to the middle column (according to the 3 column theory from Denis [3]) corresponded best with increased instability.However, there is a discrepancy between the clear biomechanical estimation of instability and the controversial discussion in clinical treatment [1]. One possible reason could be the ambiguous definition of burst fractures. To compare biomechanical results, it seems to be mandatory that fracture morphology is rated by using classification systems, which are established in clinical routine.Magerl et al. publ
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